A multi-group transmission and a method for operating a multi-group transmission are known from DE 10 2006 024 370.6. The multi-group transmission or, as the case may be, the automated multi-group manual transmission which is, for example, used in commercial vehicles comprises at least two multi-gear transmission groups that are arranged one behind the other by means of which a plurality of gears can be shifted. A first transmission group is associated with a transmission input shaft which can be connected via a starting element to a drive motor of a vehicle, while a second transmission group is associated with a main transmission shaft. In addition, a load-shifting element is provided for establishing a temporary direct connection between the transmission input shaft and the main transmission shaft by means of which, when shifting gears from an actual gear to a target gear, an intermediate gear can be shifted.
The previously described construction of the multi-group transmission makes it possible to directly connect a transmission input shaft and a transmission output shaft by means of a load-shifting element in order to reduce the rotational speed of a drive engine of a drive train of a vehicle via the starting element, such as a starting clutch, and in that way use the dynamic torque of the drive engine to engage an intermediate gear, while the shifting claws and synchronizations of the two transmission groups are switched into their neutral position during gear shifting. In that way, a drive torque of the drive unit is diverted to the intermediate gear. The second transmission group is shifted without any load and can be re-shifted after adjustment of the rotational speed via the load-shifting element of the intermediate gear which is operated in a slipping state.
Disadvantageously, however, depending on the gear change required at any given time and the number of intermediate gears during the shifting operation, no complete tractive force is supported, because the intermediate gear does not have the same gear ratio as the required target gear. The intermediate gear has an inherently smaller gear ratio than the desired target gear, because a secondary side of the load-shifting element, which is designed as a clutch, must rotate more slowly than the half of the clutch that is configured as the primary side or, as the case may be, the drive-unit side of the clutch when shifting into an intermediate gear, because otherwise the power flow in the drive train will be reversed.